DE2935805A1 - WIDE-ANGLE ZOOM LENS - Google Patents

Description

Wide-angled Zoom lens

description

The invention relates to the shortening of the focal length of a zoom lens in the close-up area, in particular a wide-angle zoom lens of the type specified in the preamble of claim .

Recently, a wide-angle zoom lens, the so-called two-group wide-angle zoom lens, has been developed, the first group of which, the front group, is a diffusing lens group and the second group, the rear group, is a converging lens group. With conventional wide-angle zoom lenses , the various unavoidable problems such as changes in spherical aberration, coma and astigmatism as a result of zooming, in particular also the very strong negative distortion on the short focal length , have been solved. In recent years, high-performance wide-angle zoom lenses have emerged. However, if the diameter of the front lens is to be reduced or if the entire lens system is to be made compact , then you can

030012/0804

the mentioned changes in the individual aberrations can no longer always be corrected satisfactorily. In particular the spherical aberration is then considerably overcorrected on the long focal length side; and if the first group is moved forward to focus on nearby objects, then the tendency becomes overcorrection becomes more pronounced and ultimately leads to extreme overcorrection of spherical aberration. Therefore, with a wide-angle zoom lens with a dispersing and a gathering group, it was not previously possible to improve the imaging properties in the close-up range, and it was therefore necessary to adjust the close-up focal length to be restricted to a comparatively large distance.

The object of the invention is therefore to provide a wide-angle zoom lens au. *; two groups, namely one dispersive and a collecting group in which the close-up focal length is shortened and in which the imaging properties are improved for short distances between objects.

The solution to this problem according to the invention is characterized in claim 1.

According to this, the wide-angle zoom lens is the object in the distance range from infinite to short object distances

03001? / 08 (U

-A-

while maintaining excellent imaging properties capable of photographing, composed of a first group / which is a diffusing lens group and a distance setting function and a second group which is a positive lens group and is located behind the first group. The first group has a dispersing, front subgroup and a collecting, rear subgroup, with the rear subgroup at a predetermined distance from the front Subgroup is located and both subgroups are in the distance setting are movable relative to each other. The first and second groups become relative to the change in magnification moved towards each other. When focusing on a nearby object, both the front subgroup and the rear subgroup Subgroup moved towards the object, but the amounts of movement of the front and rear subgroups are different, namely the air gap between these subgroups increases.

The invention is described in detail below with reference to the drawing. Show it:

1A shows the basic structure of the invented

and 1B

objective as a Gaussian

System, with Fig. 1A showing the location of each Lens groups when set to object distance infinite and Fig. 1B the

03001 2/08 (H.

Position of the individual lens groups when setting the distance to short object distances reproduce,

FIGS. 2, 3 show a first, second and third output and 4, respectively

management example of the invention

Lens in axial sectional view,

Fig. 5, 6, the state of correction of the first, double and 7

th or third embodiment ^ for example

with an image magnification ß = -0.25 on the side of the close-up focal length and the longest focal length, and

Fig. 8A, B for the first, second and third output

9A, B 10A, B example the spherical aberration

in the event that a close-up correction at an object distance of one Ti Meter carried out on the side of the longest focal length (A) or not carried out (B) will.

The basic structure of the lens according to the invention is shown in Figures 1A and 1B. FIG. 1A shows the position of the individual lens elements when setting the object distance infinite and Fig. 1B shows the position of the individual

O 3 O 0 1 2/0 B 0 4

lens elements when focusing on a nearby object. It is assumed that when an axially parallel light beam hits the first lens group L1, the height of incidence in its front subgroup L11 is given by h- ₁ and the height of incidence in its rear subgroup L12 is given by ^ ₁ 2. If the height of incidence of this light beam in the rear subgroup L12 is given by h '"with an increased air gap between the front subgroup L11 and the rear subgroup L12, then h ¹ ₂ > h .., because the front subgroup L11 is a dispersing lens group. The greater the value of this height of incidence, the stronger the influence on the spherical aberration and, since the rear subgroup L12 is a collective lens group, the correction of the spherical aberration is shifted in the direction of undercorrection with increasing height of incidence.

With this lens system, the spherical aberration is overcorrected more strongly the smaller the object distances become * however, for the reasons given above, it becomes possible to adjust the spherical aberration according to the object distance to be corrected when the air gap d between the front and rear subgroups of the first lens group is increased. The difference in the amount of movement between the front and rear subgroup is given by the difference in the remaining amount of the spherical Aberration in this lens is determined.

030012/0804

However, since the lens is a zoom lens, which occurs in such a lens system at the long focal length side spherical aberration must be adjusted so that the effect of the aforementioned Korrektionssystems for short object distances in both the close-focal length state is enhanced and in the long focal length condition.

To achieve this , the following conditions should apply:

1.2 | fJ <f ₁₂ <2.8 / fJ (1) and

O, O7 < d / ff ^ lC 0.2 (2)

Mean therein

f- the total focal length of the first group L1 f ₁₂ the total focal length of the rear subgroup L12 of the first group L1 and

d is the distance between the image-side main plane of the front subgroup L11 and the object-side main plane of the rear subgroup L12 of the first lens group L1 at the object distance infinite.

Condition 1 relates to the power distribution on the front and rear sub-groups of the first lens group L1. The spherical aberration tends to be significantly overcorrected on the long focal length side at short distances

03001 2/0804

s * as *

it is therefore necessary to infinitely undercorrect the spherical aberration at the object distance keep. When the lower limit of Condition 1 is exceeded, the spherical aberration becomes the long-focus one Page overcorrected excessively, and this then makes even the above-mentioned close-up correction mechanism less effective. If the upper limit of Formula 1 is exceeded, then the spherical aberration is unduly undercorrected, and the use of the above-mentioned close-up correction mechanism becomes meaningless.

Condition 2 is used to suppress the change in the spherical aberration insofar as this is dependent on a change in the Focal length originates. If the lower limit of this formula is exceeded, it becomes impossible to change the focal length correct the resulting change in spherical aberration. When the upper limit of this condition is exceeded becomes, the first lens group becomes too thick and the image-side main plane of the first group shifts to Object side, which reduces the air gap between the first and second group and thus the range of displacement of the two groups. This undesirably reduces the zoom ratio.

If the lens system is not one of the above Conditions 1 and 2 are met, then the corrective effect is

030012/0804

on the spherical aberration, especially on the long focal length Side with a setting on a nearby object, worse.

Accordingly, in the manner described here, the mapping behavior for objects at short object distances improved and the close-up focal length can be shortened greatly, and it becomes possible, the aberrations in a well corrected state on the long focal length side, for example for f = 70 mm and hold for a magnification of, for example, β = -0.25 or closer.

Three embodiments are described below.

The first embodiment is shown in FIG. After that, L11 of the first group are in the front subgroup L1 two diffusing meniscus lenses on each convex anterior surface. In the rear subgroup L 12 there is a converging meniscus lens also convex front surface.

In the second exemplary embodiment, which is shown in FIG. 3, L11 of the first group are located in the front subgroup L1 three lens elements, namely, enumerated from the object side, a converging lens with a more strongly curved front surface, a diverging lens with a more strongly curved rear surface and a negative meniscus lens with a convex front surface.

030012/0804

A converging meniscus lens is located in the rear subgroup L12 convex front surface.

In the third exemplary embodiment, which is shown in FIG. 4, the first lens group is located in the front subgroup L11 L1 three components, namely - seen from the object side - a diffusing meniscus lens with a convex front surface, a converging lens and a diverging lens with the more strongly curved rear surface. In the rear subgroup L12 is a converging meniscus lens with a convex front surface.

For the second group L2, it is desirable in all cases that it is made up of at least five components. These components have the form shown in FIGS. 2 to 4.

The numerical data of these embodiments are below reproduced. The sizes used in FIGS. 2 to 4 and in the tables below are the usual ones Meaning; so it mean

r ₁ , r ~ .... the radii of curvature of the individual lens _{elements d 1} , d ₁ .... the axial lens thicknesses or air gaps, η and ν the refractive indices or Abbe numbers of the individual lens glasses,
all consecutively numbered from the object side.

030012/0804

First Embodiment (Fig. 2)

Total focal length : f from 36.0 to 68.6 Angle of view: 2tu from 31 ° to 17.6 ° Relative aperture f: 3.5

^r i ⁼ 43.640 ^d 1 ⁼ 1.5 ⁿ 1 ⁼ 1.71300 ^V 1 ⁼ until 11.3 (ß = -0.25) 0.05 ^V 4 ⁼ 53.9 ^r 2 ⁼ 25,862 ^d 2 ⁼ 4.9 n ₃ = 1.80518 ^V 3 ^{= r} 3 ⁼ 97.646 ^d 3 = 2.3 ⁿ 2 ⁼ 1.69680 ^V 2 ⁼ from 32.85 to ^V 5 ⁼ 55.6 ^r 4 ⁼ 34,089 ^d 4 ⁼ Close range correction distance of ⁿ 4 ⁼ 1.62041 10.7 (*>) ^V 6 ^{= r} 5 ⁼ 32,807 ^d 5 ■ 3.8 ⁿ 5 ⁼ 1.62041 25.5 ^r 6 ⁼ 43,313 ^d 6 ■ variable ^V 7 ^{= r} 7 ⁼ 38.8OO ^d 7 ■ 8.6 ⁿ 6 ⁼ 1.80518 60.3 ^r 8 ⁼ -118.771 ^d 8 ■ 2.5 ^V 8 ^{= r} 9 ⁼ 21,150 ^d 9 = 4.9 n ₇ = 1.62588 60.3 ^r 1O ⁼ 67.565 ^d 10 ⁼ 2.7 ^r 11 ⁼ -111.186 ^d n ⁼ 4.2 ⁿ 8 ⁼ 1.62588 25.5 ^r 12 ⁼ 20.265 ^d 12 ⁼ 3.0 ^r 13 ⁼ -100.634 ^d 13 ⁼ 3.2 35.6 ^r 14 ⁼ -29.367 ^d 14 ⁼ 0.1 ^r 15 ⁼ 5O, O24 ^d 15 ⁼ 2.5 35.6 ^r 16 ⁼ 110.281

Back focus Bf from 42.7 to 65.2 Close range correction distance 10.7 (<- c) to 11.3 (ß = -0.25)

030012/0804

Second embodiment (Fig. 3)

Total focal length: f from 36.0 to 68.8 Angle of view: 2w from 31 ° to 17.4 ° Relative opening f: 3.5

"1 -

^r 3 ^=
r 4 ⁼

^r 5 ⁼
r, - =

^r 7 ⁼

^r 8 ⁼

^r 9 ⁼

^r 1O ⁼

^r 12 ^=
r 13 ^=
r 14 ^=
r 15 ^=
r 16 ⁼

^r 18 ⁼
r ₁₉ -

61, 849

-1037.164

1,000,000

23,900

178.734

42.672

34.110 81.925 72.840

-72.840

-144.173

26.644

246.000 20.743 27.990 -370.855 18.700 64.660

-39.168

^d 1 ⁼ d-, =

d ₅ =

d, =

- 1.60323

n ₂ = 1.67790

= 55.5

1.5 n ₃ = 1.71300 V ₃ = 53.9

Close range correction distance from 5.7 (<^) to 6.2 (ß = -0.25)

d ₇ = 3.9

^d 8 ^d 9 n ₄ = 1.59507 V ₄ = 35.6

= variable from 33.45 to 0.65

^d 10 ⁼

^d 12 ^{= d} 13 ^{= d} 14 ^{= d} 15 ^{= d} 16 ^{= d} 17 ^{= d} 18 ⁼

3.5

1.0

0.1

4.9

0.1

4.5

3.9

1.5

5.2

3.8 n ₅ = 1.62041
n, = 1.80518

n _? = 1.51118

V ₅ = 60.3 ν. = 25.5

V ₇ = 50.9

n _Q = 1.51680 v _Q = 64.2

^l 8

1.80518

n ₁₀ = 1.64821

V ₉ = 25.5

= 33.8

Back focus Bf from 43.7 to 66.3

Noih range correction distance: dg = 5.7 () to 6.2 (B = -0.25) 10

030012/0804

Third embodiment (Fig. 4)

Total focal length f from 36.0 to 68.8 field angle 2w from 31 ° to 17.4 ° Relative opening f: 3.5

^r 1 ⁼ 50.379 ^r 2 ⁼ 27,469 ^r 3 ⁼ 670.373 ^r 4 ⁼ -114.009 ^r 5 ⁼ CP ^r 6 ⁼ 32,531 ^r 7 ⁼ 35.195 ^r 8 ⁼ 57.902 ^r 9 ⁼ 101.102 ^r 10 ⁼ -763.611 ^r n ⁼ 28.387 ^r i2 ⁼ -449.780 ^r 13 ⁼ 19,335 ^r 14 ⁼ 37.463 ^r 15 ⁼ -564,061 ^r i6 ⁼ 16.279 ^r 17 ⁼ 44.719 -56.453

^d 1 ■ 1.3 ⁿ 1 ⁼ 1 , 74443 ^d 2 ⁼ 6.3 ^d 3 ⁼ 3.5 ⁿ 2 ⁼ 1 , 51680 ^d 4 ⁼ 0.1 ^d 5 = 1.8 n ₃ = 1 , 71300

= 49.4

= 64.2

= 53.9

and v
8.4 (O to 9.0 (ß = -0.25)

d, = close range correction distance of ο

= 26.5

= 64.2

= 70.1

= 70.1

= 25.5

Back focus Bf from 43.8 to 68.7 Close range correction distance: d _c = 8.4 (^) to 9.0 (ß = -0.25)

¹¹ 030012/0804

^d 7 ⁼ 3.4 ⁿ 4 ^{= n} 5 ⁼ 1.76182 ^d 8 ⁼ variable from 28.93 b.s ^d 9 ⁼ 3.0 ⁿ 6 ⁼ 1.51680 ^d 10 ⁼ 0.1 ^d 1l- 6.4 ⁿ 7 ⁼ 1.52000 ^d 12 ⁼ 0.1 ^d 13 ⁼ 5.9 ⁿ 8 ⁼ 1.520OO ^d 14 ⁼ 4.0 ^d 15 ⁼ 1.4 ⁿ 9 ⁼ 1.80518 ^d 16 ⁼ 3.85 ^d 17 ⁼ 4.1 1.67270

The individual values that form the basic structure of the three exemplary embodiments are given below.

First
Execution
example second
Execution
example third
Execution
example !
j ^f 1 -59.966 -59.942 -53,000: ^f 12 144.643 95.312 110.660 ^f i ₂ // ^f i ' 2,412 1,590 2.090 d 6.79 5.69 8.82 0.11 0.09 I. 0.16

The lens structure of the first, second and third embodiments is shown in FIGS. 2, 3 and 4, respectively. Your correctional states for a photographic magnification of β = -0.25 on the side of the shortest focal length on the side of the longest focal lengths are shown in FIGS. 5, 6 and 7, respectively.

Furthermore, the spherical aberration of the first, second and third embodiments is shown in FIGS. 8, 9 and 10, respectively shown for the two cases that the close range correctJon at an object distance of one meter (photographic magnification ß = 0.07) on the side of the longest focal length through

030012 / 080A

is carried out (a) or not carried out (b).

From the correction state diagrams shown, it can be seen that the individual aberrations, in particular the spherical aberration at close object distances, are significantly improved and excellent imaging behavior is present for all exemplary embodiments.

030012/0804

Claims (1)

BLUMBACH · WESER · BERGEN - KRAMER PATENT LAWYERS IN MUNICH AND WIESBADEN Patentconsult RadedcestraBe 43 8000 Munich 60 Telephone (089) 883603/883604 Telex 05-212313 Telegrams Patentconsult Palentconsull Sonnenberger Straße 43 6200 Wiesbaden Telephone (06121) 562943/561998 Telex 04-136237 Telegrams Palentconsult Nippon Kogaku K.K. Case 414 Claim Wide-angle zoom lens, which is built up from the object side from a first, dispersing lens group (L1) and a second, converging lens group (L2) and in which the change in magnification occurs through a relative movement of the first and second group to each other in the direction of the optical axis , while the distance adjustment is done by moving the first group independently, characterized in that - The first group (L1) from a dispersing front sub-group (L11) and a collecting, rear sub-group (L12) is constructed and - Both subgroups are moved relative to one another in the direction of the optical axis when setting the distance. Munich: R. Kramer Dipl.-Ing. . W. Weser Dipl.-Phys. Dr. rer. nal. · HP Brehm Dipl -Cherr. Or. Phil. n / A! Wiesbaden: P. G. Blumbach Dipl.-Ing. · P. Bergen Dipl.-Ing. Dr jur · G. Zwirner Dipl.-Ing. Dipl -W ing 030-12 / 0804